The effects of a 7% CHO-electrolyte drink and a placebo (water) on physiological responses, hydration status, and exercise performance were evaluated during a simulated outdoor 40 km road race under warm, humid conditions. Ss (N = 8) were highly trained, heat acclimatized, male distance runners. Beverages were consumed during a brief respite once every 5 km loop of the test track.

CHO-electrolyte trials showed significantly higher blood glucose levels throughout the trial and recovery periods than did placebos. Percent of VO2max declined drastically during the last 20 km in the placebo condition, but remained steady in the CHO-electrolyte condition. Running time was also significantly faster in the CHO-electrolyte group.

Implication. The consumption of a 7% CHO-electrolyte solution is similar to water as a fluid replacement in terms of thermoregulation, maintenance of physiological function, and hydration status. However, the CHO-electrolyte solution increased blood glucose levels and had a significant ergogenic effect on prolonged running. This is a significant advantage when competing in the heat.